The present invention concerns overhead door assemblies and their use in temperature controlled storage structures for temporary storage of perishable items such as various types of foods.
The shipping of highly perishable items of food by air is complicated by the fact that the food must be stored at reduced temperatures when stored between flights. Existing storage facilities at airports do not permit convenient storage and retrieval of small food shipments nor expeditious handling of same by ground personnel. Accordingly, time is often lost in handling such shipments to the extent the perishable article spoils. To expedite the handling of food articles it has been found desirable to store same in storage structures arranged in rows or in place in rows on mobile bases with each having an overhead door to facilitate rapid transfer of articles into and out of the structures.
U.S. Pat. No. 4,901,538 shows a system for refrigerating perishables while in place in the air cargo container. A wheel supported refrigerator unit discharges cold air through conduits into the containers. Problems encountered in storing perishable articles at airports are discussed in this patent.
U.S. Pat. No. 3,507,322 discloses a system for the shipping and storage of perishable food articles in cabinets each with a pair of conduits for coupling to a piping circuit carrying a heating or cooling medium with quick disconnects provided for conduit attachment.
In a typical overhead door installation a certain amount of clearance is necessary to permit unobstructed, vertical door opening and closing movement along upright rails adjacent the doorway opening. In structures not requiring a controlled temperature e.g., a garage, a certain amount of such clearance is acceptable. An overhead type sealable door for walk in temperature controlled storage structure is not found in the prior art to the extent known.